Overpaneling over a 100% of what a controller can take. Offgrid

Derka181 · May 11, 2023

I’m going to overpanel my 40a renogy solar controller (12v / 520W) and in theory it should work. My renogy controller is 100vdc and my panels are 535w each. Each panel has approx 50v and 12.5 amps. I will be wiring these panels in parallel using 8 awg wire. 8 awg wire can do 40amp . So these 2 panels in parallel will only be at approximately 25amps at peak times and my solar controller with only be using 50v of my 100vdc. I heard a guy say that the panels don’t push power to the control the controller takes what it needs from the panels. And gave an example like this…..A light in your car uses 20w/ 1amp. You battery doesn’t push its full power to the light. Think of your solar controller as the light . The light will only take what it needs from the battery, as long as you are below the specs on vdc.

Am I wrong, and is this a bad idea?

SoakedUp · May 11, 2023

I just had 1200 watts (4 320 renogy panels wired in 2s2p) connected to a renogy rover 40a CC for the last 9 months in very sunny souther California desert. Didn’t seem to be a problem other than I was almost constantly pulling the max amps out of the controller and it would get fairly warm if ambient temps were in the 80s. I put a fan on it and it seemed to take care of the problem. Also my battery would go into float by 10am so overheating wasn’t too much of a concern.

chrisski · May 11, 2023

I do overpaneling with a 15 amp Victron controller I’ve used over 100 times and have once had an overamperage error, but nothing hat slowed production.

Really comes down to you accepting the risk of something going wrong, and has mentioned, the possible shorter life of the charge controller running all out possibly all day. My SCC is a portable setup sitting outside.

timselectric · May 12, 2023

Overpaneling is very common.
Lots of benefit. No down side.

squowse · May 12, 2023

Derka181 said:
I’m going to overpanel my 40a renogy solar controller (12v / 520W) and in theory it should work. My renogy controller is 100vdc and my panels are 535w each. Each panel has approx 50v and 12.5 amps. I will be wiring these panels in parallel using 8 awg wire. 8 awg wire can do 40amp . So these 2 panels in parallel will only be at approximately 25amps at peak times and my solar controller with only be using 50v of my 100vdc. I heard a guy say that the panels don’t push power to the control the controller takes what it needs from the panels. And gave an example like this…..A light in your car uses 20w/ 1amp. You battery doesn’t push its full power to the light. Think of your solar controller as the light . The light will only take what it needs from the battery, as long as you are below the specs on vdc.

Am I wrong, and is this a bad idea?

Victron give very detailed guidance on overpanelling. Renogy/Epever etc just seem to say 120%, 150% etc. Its mostly hownthe controller would respond to a malfunction. Eg whether it would melt down.

littleharbor2 · May 12, 2023

Here's an older EPever over paneling chart.

pollenface · May 12, 2023

Derka181 said:
I heard a guy say that the panels don’t push power to the control the controller takes what it needs from the panels.

That is very much true, you've got the right idea.

Bluedog225 · May 12, 2023

I don’t understand the straight polarity and reverse polarity in the above post.

pollenface · May 12, 2023

I think it means connected correctly vs connected with the polarity in reverse (which you shouldn't do if you're paying attention

)

Derka181 · May 12, 2023

SoakedUp said:
I just had 1200 watts (4 320 renogy panels wired in 2s2p) connected to a renogy rover 40a CC for the last 9 months in very sunny souther California desert. Didn’t seem to be a problem other than I was almost constantly pulling the max amps out of the controller and it would get fairly warm if ambient temps were in the 80s. I put a fan on it and it seemed to take care of the problem. Also my battery would go into float by 10am so overheating wasn’t too much of a concern.

Are you using 8 awg wire or 10 awg?

Hogheavenfarm · May 12, 2023

I ran 1.4kw through my Renogy Rover 40amp controller for most of last year, no issues at all.

Derka181 · May 12, 2023

Hogheavenfarm said:
I ran 1.4kw through my Renogy Rover 40amp controller for most of last year, no issues at all.

Were you using 10 or 8 awg wire

Crowz · May 12, 2023

Bluedog225 said:
I don’t understand the straight polarity and reverse polarity in the above post.

My take on it is hooked up correctly "straight polarity" it just takes what it needs so no danger going over like crazy.

Hook it up backwards by mistake "reverse polarity" the built in reverse polarity protection which keeps from frying the controller can be overloaded when over paneled and BOOM goes the controller aka fried.

SoakedUp · May 12, 2023

Derka181 said:
Are you using 8 awg wire or 10 awg?

10 awg. My panels ISC is about 10 amps so two in parallel only puts out about 20amps max. Panels to SCC is under 40ft.

Hogheavenfarm · May 12, 2023

I was only using 10 awg as well, no issues with that. all were 5.5 amp panels in parallel.

chrisski · May 12, 2023

I also want to add for my 15 amp Victron SCC that maxes out at 24 volt absorption voltage at 420 watts I put 900 watts of panels on it.

This Victron allows me to hook panels up where open circuit amps exceed the 15 amps of the controller.

My actual max amps in at 66 volts us 13.5 amps, but the SCC is limited to

15 amps out X absorption voltage = 420 watts

So even though my panel watts exceed the wattage max out of the SCC by two times, I could add more panels to stay under the limit.

timselectric · May 12, 2023

I had over 80a worth of panels connected to an 18a max SCC. It ran like this for several months.
No issues at all. It just pulled the 18a for most of the day.

JWLV · May 12, 2023

Absolutely no problems with overpaneling. I have 3750 watts in panels going to a Growatt 2000w inverter. At mid day, the inverter takes 2200w. It still wouldn't be a problem if I had 10000 watts in panels. The inverter will only take what it needs. The only risk is if somehow the MC4 cable got cut or damaged in such a way that it would cause a short, it would burn up pretty quickly, rather than burn up slowly. But then burning up quickly might be better, since it would be kind of like a fuse.

squowse · May 13, 2023

littleharbor2 said:
Here's an older EPever over paneling chart.
View attachment 148849

Wow thats a lot more generous than ones ive seen before. 300% of charge rating.

squowse · May 13, 2023

timselectric said:
I had over 80a worth of panels connected to an 18a max SCC. It ran like this for several months.
No issues at all. It just pulled the 18a for most of the day.

Sounds like you’re mixing up the PV current and charge current?

Overpaneling over a 100% of what a controller can take. Offgrid

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